1. Field of the Invention
This invention relates to electrostatic pinning, and more particularly relates to an electrostatic apparatus and method for opening flexible liner bags within containers and maintaining such liners in spread apart disposition prior to filling with material.
The apparatus and method of the present invention is especially concerned with A.C. electrostatic ionizing means for directing a stream of bipolar air ions toward the outer walls of a container and D.C. electrostatic charging means for directing an ion wind of a single polarity toward the interior of the liner positioned within the container in spread apart disposition. The liner and the container will become charged to opposite polarities causing electrostatic pinning of the open liner to the interior walls of the container while the net charge on the liner-container package remains essentially neutral, thereby enabling the liner to be easily filled with its intended material.
2. Prior Art
In U.S. Pat. No. 4,657,151 and U.S. Pat. No. 4,558,792 to Cabernich, there are shown semi-rigid outer shells encapsulating coextensive inner liners weakly adhered thereto for the purpose of use as a nipple or nursing containers for feeding nipples.
In U.S. Pat. No. 3,892,614 (Levy), there is shown and described electrostatic laminating apparatus in which two or more sheets or articles to be pinned together are passed in close proximity or in contact with each other through an electric field. The field includes a first ionizing device for impinging unipolar ions of a particular polarity toward one side of the adjacent sheets while simultaneously directing ions of both polarities toward the other side of the sandwich. Although charges of opposite polarity appear on abutting surfaces of the sandwich, the resultant net charge on the electrostatically pinned laminate is neutral.
U.S. Pat. No. 3,844,657 (Schweriner) shows and describes a contact printing apparatus in which a laminar flow A.C. ionized air stream is directed over a sandwich of sheets (such as a negative and positive printing paper) resting flat on a surface while a D.C. generator is coupled to the surface to hold down the photosensitive film and negative to each other preparatory to exposure to light.
3. Objectives of the Invention
The present invention is especially useful for opening of flexible liners in containers, such as boxes or cartons, and maintain these liner bags in open disposition prior to filling. A typical application for spreading apart and holding such flexible liner bags open is in connection with filling operations of the food industry, for example in loading a box of dry cereal, crackers, cake mixes and snacks. It is important for the liner bag to be open when the liner bag is being loaded by the filling machine--otherwise the fill will not enter the bag with the consequent result that a misfill will occur with packaging rejection.
Existing processes depend upon the stiffness of the liner to keep the bag open until the filling operation is performed. However, because of such variables as warp in liner material and size variations in cut material, these liners have a tendency to partially close prior to and during filling. The present method electrostatically pins the liner bag to the inside of the container and in the process opens said liner bags. Using electrostatic pinning to open the liner bag and further to maintain such liner bags in open disposition eliminates a troublesome variable in the filling procedure with less waste occurring during packaging.
It is therefore an object of this invention to provide an apparatus and method for electrostatically opening flexible liners stuffed in their containers and maintaining such liners in spread apart disposition prior to and during filling.
Another object of this invention is to provide an apparatus and method for electrostatically pinning flexible liners to the inside walls of their containers and opening the liner bags in the process prior to filling.
Still another object of this invention is to provide an electrostatic apparatus and method for opening flexible liner bags contained within cartons or boxes preparatory to filling the liner bags and maintaining said liner bags in spaced apart disposition during filling while keeping the total package electrostatically neutral at completion of operations.
Yet another object of this invention is to provide an electrostatic apparatus and method for electrostatically pinning flexible liner bags to the interior walls of a container by directing a stream of ions of a single polarity (D.C. negative or D.C. positive ions) toward the bag while symmetrically directing a stream of A.C. ions of both polarities toward the outside of the container thereby causing an electric field to be developed between a D.C. charging bar emitting the single polarity ions and an A.C. static bar emitting the dual polarity ions whereby an ion wind is produced that drives the D.C. charges deep into the liner bag for efficacious pinning.
Other objects of this invention are to provide an improved device and method of the character described which is easily and economically produced, sturdy in construction and both highly efficient and effective in operation.